Conventionally, a scrub soap combined with a scrub agent is provided to improve an effect on removal of such as dirt on the skin or old dead skin cells of the skin. The scrub agent can physically remove such as dirt on the skin or dead skin cell of the skin by rubbing and adsorbing so that cleaning effect of the soap can be increased.
A material as the scrub agent includes e.g. rice bran, azuki bean, toasted soybean flour, konjac, seaweed, corn flour, oatmeal, crystalline cellulose, apricot seeds, walnut shell particles, polyethylene, polystyrene, nylon, alumina, silica, talc, volcanic glassy sediment, and shirasu.
The pore size on the human face is average 80-150 μm and if the particle size of the scrub agent combined with the soap is smaller than the pore, such as pore clogging dirt or dead skin cells can be efficiently removed.
Further, it is ideal to provide a scrub soap having high cleaning and scrubbing effect despite a small amount in use, in which a combined amount of the scrub agent is as large as possible. If the amount used is suppressed, the environment load can be decreased.
On the other hand, the larger amount of the scrub agent is combined the more likely the separation between the scrub agent and the liquid component occurs during manufacturing, and it is difficult to make the product keeping the homogeneous mixed state of materials because the scrub agent precipitates.
Further, it is problematic that when the large amount of the scrub agent, which is fine powder, are combined, the mechanical mixing becomes impossible and productivity thereof extremely decrease because viscosity of the mixture of materials extremely increases and fluidity thereof decreases.
In Patent Document 1, a method for manufacturing a scrub soap is disclosed, in which a large amount of scrub agents is combined. While, medium chain fatty acid esters or ethyl alcohol as a fluidization auxiliary agent is added in separate to increase fluidity of materials. Accordingly, because the number of materials used increases, an adjustment of the combination amount of materials becomes complicated and the number of steps of manufacturing process consequently increases. In addition, it is problematic that affinity of medium chain fatty acid esters for a soap is bad and the soap likely separates therefrom. Further, while a means to increase fluidity of materials is disclosed in Patent Document 1, no means to solve the precipitation problem of the scrub agent resulting from separation between the scrub agent and the liquid component is disclosed.
Further, a volcanic glassy sediment represented by shirasu as a raw material for a scrub agent is noticeable because of high cleaning effect thereof. In Patent Document 2, the inventor of the present invention proposed the method to manufacture a scrub soap combined with a shirasu balloon as the scrub agent thereof, which is obtained by quellung processing of shirasu. A scrub soap manufactured by using such method has a property of which the soap component of the soap formed inside of the hollow shirasu balloon is gradually eluted therefrom in use and accordingly bubbling is characteristically long-lasting.
However, in contrast to improved long-lasting bubbling due to forming the soap inside the shirasu balloon, it is problematic that lathering (foaming at the beginning of the use of the scrub soap) is sacrificed.
Then, when the shirasu balloon and the shirasu with no hollow were mixed to make a scrub agent to provide both long-lasting bubbling and good lathering, viscosity on manufacturing becomes very high so that mechanical mixing and homogeneous dispersion of the scrub agent become difficult issues despite the same combination amount used as before.